First study of the CP-violating phase and decay-width difference in $B_s^0\to\psi(2S)\phi$ decays

TL;DR

This study presents the first measurement of the CP-violating phase and decay-width difference in $B_s^0$ decays involving the $ ext{psi}(2S)$ resonance, using LHCb data to advance understanding of CP violation in the $B_s^0$ system.

Contribution

It provides the first measurement of $ ext{CP}$-violating phase and decay-width difference in $B_s^0 o ext{psi}(2S) ext{phi}$ decays, expanding the scope of CP violation studies.

Findings

Measured $ ext{CP}$-violating phase $\phi_s = 0.23^{+0.29}_{-0.28} ext{ rad}$

Measured decay-width difference $\Delta ext{G}_s = 0.066^{+0.041}_{-0.044} ext{ ps}^{-1}$

First such measurements in a decay with $ ext{psi}(2S)$ resonance.

Abstract

A time-dependent angular analysis of $B_s^0\to\psi(2S)\phi$ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0\invfb collected during Run 1 of the LHC. The CP-violating phase and decay-width difference of the $B_s^0$ system are measured to be $\phi_s = 0.23^{+0.29}_{-0.28} \pm 0.02$ rad and $\Delta\Gamma_s = 0.066^{+0.041}_{-0.044} \pm 0.007$ ps$^{-1}$, respectively, where the first uncertainty is statistical and the second systematic. This is the first time that $\phi_s$ and $\Delta\Gamma_s$ have been measured in a decay containing the $\psi(2S)$ resonance.